584 research outputs found

    Numerical Simulation Analysis of Water Injection Seepage Law in Micro Porous Structure of Coal

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    In this paper, a nano Voxel X-ray 3D microscope is used to scan the long flame coal samples and to reconstruct the 3D pore structure by the use of microscopic computed tomography. With image segmentation technique, a model of micro-pore structure of coal is obtained from the reconstructed coal. With different planes selected as seepage inlets, a numerical simulation of low-pressure water seepage is conducted. Studies show that water pressure gradually decreases along the direction of water seepage and reaches the maximum at the pore-pipes with good connectivity near the inlet. Due to the difference between the structure and development direction of pores in the three dimensions, there is an optimal seepage outlet that is most appropriately corresponding to each seepage inlet. When different planes are selected as seepage inlets, the velocity of each seepage outlet is positively correlated with the seepage mass flow rate at the outlet

    Photoproduction of the charged top-pions at the LHeC

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    The top triangle moose (TTM)(TTM) model, which can be seen as the deconstructed version of the topcolor-assisted technicolor (TC2TC2) model, predicts the existence of the charged top-pions πt± \pi_{t}^{\pm} in low energy spectrum. In the context of this model, we consider photoproduction of πt±\pi^{\pm}_{t} via the subprocesses γbtπt\gamma b\to t \pi_{t}^{-} and γbˉtˉπt+\gamma \bar{b}\to \bar{t} \pi_{t}^{+} at the large hadron-electron collider (LHeCLHeC), in which high energy photon beams are generated by using the Compton backscatting method. We find that, as long as the charged top-pions are not too heavy, they can be abundantly produced via γb\gamma b collision.Comment: 16 pages, 5 figure

    Diacetatobis[1,3-bis­(benzimidazol-2-yl)benzene]zinc(II) dihydrate

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    In the title complex, [Zn(CH3COO)2(C20H14N4)2]·2H2O, the ZnII atom, which lies on a crystallographic twofold axis, is coordinated by two O atoms of two acetate ligands and two N atoms from two 1,3-bis­(benzimidazol-2-yl)benzene ligands in a distorted tetra­hedral geometry. The complex mol­ecules and solvent water mol­ecules are connected via O—H⋯N, O—H⋯O and N—H⋯O hydrogen bonds, forming a three-dimensional network

    Individual and Group Dynamics in Purchasing Activity

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    As a major part of the daily operation in an enterprise, purchasing frequency is of constant change. Recent approaches on the human dynamics can provide some new insights into the economic behaviors of companies in the supply chain. This paper captures the attributes of creation times of purchase orders to an individual vendor, as well as to all vendors, and further investigates whether they have some kind of dynamics by applying logarithmic binning to the construction of distribution plot. It's found that the former displays a power-law distribution with approximate exponent 2.0, while the latter is fitted by a mixture distribution with both power-law and exponential characteristics. Obviously, two distinctive characteristics are presented for the interval time distribution from the perspective of individual dynamics and group dynamics. Actually, this mixing feature can be attributed to the fitting deviations as they are negligible for individual dynamics, but those of different vendors are cumulated and then lead to an exponential factor for group dynamics. To better describe the mechanism generating the heterogeneity of purchase order assignment process from the objective company to all its vendors, a model driven by product life cycle is introduced, and then the analytical distribution and the simulation result are obtained, which are in good line with the empirical data

    Machine learning prediction of motor function in chronic stroke patients: a systematic review and meta-analysis

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    BackgroundRecent studies have reported that machine learning (ML), with a relatively strong capacity for processing non-linear data and adaptive ability, could improve the accuracy and efficiency of prediction. The article summarizes the published studies on ML models that predict motor function 3–6 months post-stroke.MethodsA systematic literature search was conducted in PubMed, Embase, Cochorane and Web of Science as of April 3, 2023 for studies on ML prediction of motor function in stroke patients. The quality of the literature was assessed using the Prediction model Risk Of Bias Assessment Tool (PROBAST). A random-effects model was preferred for meta-analysis using R4.2.0 because of the different variables and parameters.ResultsA total of 44 studies were included in this meta-analysis, involving 72,368 patients and 136 models. Models were categorized into subgroups according to the predicted outcome Modified Rankin Scale cut-off value and whether they were constructed based on radiomics. C-statistics, sensitivity, and specificity were calculated. The random-effects model showed that the C-statistics of all models were 0.81 (95% CI: 0.79; 0.83) in the training set and 0.82 (95% CI: 0.80; 0.85) in the validation set. According to different Modified Rankin Scale cut-off values, C-statistics of ML models predicting Modified Rankin Scale>2(used most widely) in stroke patients were 0.81 (95% CI: 0.78; 0.84) in the training set, and 0.84 (95% CI: 0.81; 0.87) in the validation set. C-statistics of radiomics-based ML models in the training set and validation set were 0.81 (95% CI: 0.78; 0.84) and 0.87 (95% CI: 0.83; 0.90), respectively.ConclusionML can be used as an assessment tool for predicting the motor function in patients with 3–6 months of post-stroke. Additionally, the study found that ML models with radiomics as a predictive variable were also demonstrated to have good predictive capabilities. This systematic review provides valuable guidance for the future optimization of ML prediction systems that predict poor motor outcomes in stroke patients.Systematic review registrationhttps://www.crd.york.ac.uk/prospero/display_record.php?ID=CRD42022335260, identifier: CRD42022335260

    Proteomic analysis of sex conversion induced by CPPU in male grapevine of Vitis amurensis

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    If N-(2-chloro-4-pyridyl)-N′-phenylurea (CPPU) could induce sex conversion in male plants of Vitis amurensis Rupr., this would reduce blindness of selection for male parents according to the fruit characters in cold-tolerant and disease-tolerant grape crossbreeding. Flower bud samples of male plants were treated with 100 mg∙L-1 CPPU at 15 days before anthesis. Two-dimensional gel electrophoresis (2-DE) was used to analyze the proteins related to sex conversion at different development time points. More than 600 protein spots were detected. Among them, 31 differentially expressed proteins were identified by MALDI-TOF/TOF, and 24 protein spots could be assigned to a probable function. Seventeen proteins participated in the sex conversion and with complex interaction. Sex conversion might receive the ROS signal in the beginning, and then pollen tube proteins were proposed to down-regulate to repress the stamen development, while the up-regulated cell elongation protein might promote the development of pistil. Adenine phosphoribosyl transferase 3 was proposed as the key protein in the sex organ conversion that was up-regulated by CPPU in the male V. amurensis achieving the ability to fruit in the end.

    Functional Conservation of the Drosophila gooseberry Gene and Its Evolutionary Alleles

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    The Drosophila Pax gene gooseberry (gsb) is required for development of the larval cuticle and CNS, survival to adulthood, and male fertility. These functions can be rescued in gsb mutants by two gsb evolutionary alleles, gsb-Prd and gsb-Pax3, which express the Drosophila Paired and mouse Pax3 proteins under the control of gooseberry cis-regulatory region. Therefore, both Paired and Pax3 proteins have conserved all the Gsb functions that are required for survival of embryos to fertile adults, despite the divergent primary sequences in their C-terminal halves. As gsb-Prd and gsb-Pax3 uncover a gsb function involved in male fertility, construction of evolutionary alleles may provide a powerful strategy to dissect hitherto unknown gene functions. Our results provide further evidence for the essential role of cis-regulatory regions in the functional diversification of duplicated genes during evolution

    Precision measurement of the branching fractions of J/psi -> pi+pi-pi0 and psi' -> pi+pi-pi0

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    We study the decays of the J/psi and psi' mesons to pi+pi-pi0 using data samples at both resonances collected with the BES III detector in 2009. We measure the corresponding branching fractions with unprecedented precision and provide mass spectra and Dalitz plots. The branching fraction for J/psi -> pi+pi-pi0 is determined to be (2.137 +- 0.004 (stat.) +0.058-0.056 (syst.) +0.027-0.026 (norm.))*10-2, and the branching fraction for psi' -> pi+pi-pi0 is measured as (2.14 +- 0.03 (stat.) +0.08-0.07 (syst.) +0.09-0.08 (norm.))*10-4. The J/psi decay is found to be dominated by an intermediate rho(770) state, whereas the psi' decay is dominated by di-pion masses around 2.2 GeV/c2, leading to strikingly different Dalitz distributions.Comment: 15 pages, 2 figure
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